A parabolic trough power plant generates electricity using concentrated sunlight as the heat source for its power cycle. Most commonly rows of single-axis-tracking, linear parabolic mirrors form a solar field that concentrate beam radiation onto tubular receivers which are also known as heat collection elements (HCEs). See, e.g., FIG. 1A. The HCE's are located along the focal line of each parabolic trough. Heat-transfer fluid pumped through the HCE's is heated by the solar heated receiver walls on which the parabolic mirrors focus solar radiation. See, e.g., FIG. 1B. After being heated by the solar field, the heat-transfer fluid is typically used generate high-pressure superheated steam in a series of heat exchangers. Most commonly, the energy in the steam is converted to electricity in a Rankine steam turbine power cycle. After passing through the heat exchangers, the cooled heat transfer fluid is recirculated through the HCEs.